Method and apparatus for the carbonization of fluidized materials



Dec. 5, 1961 P. FOCH 3,011,953

METHOD AND APPARATUS FOR THE CARBONIZATION 0F FLUIDIZED MATERIALS FiledJuly 2, 1958 2 Sheets-Sheet 1 7 milk wi cs Maw Dec. 5, 1961 c 3,011,953

METHOD AND APPARATUS FOR THE CARBONIZATION OF FLUIDIZED MATERIALS FiledJuly 2, 1958 2 Sheets-Sheet 2 7 fiflk (A), LocCS United States Patent3,911,953 METHOD AND APPARATUS FOR THE CARBGNI- ZATION 0F FLUIDIZEDMATERIALS Pierre Foch, Forbach, Moselle, France, assignor toCharbonnages de France, Paris, France, a public institution of theFrench Republic Filed July 2, 1958, Ser. No. 745,266

Claims. (Cl. 2G2--6) This invention relates to a method for the thermaltreatment of coal using the fluidised bed technique. It also relates toan apparatus for carrying out this method in a continuous manner.

The invention concerns improvements in methods in which coal fines aresubjected to the action of heat in a fluidised bed, in the presence of afluidising gas, by a partial combustion of the mass. t applies, moregenerally, to carbonisation methods at high or low temperature whereinthe main object to be achieved is the production of granulated orpulverulent coke or semi-coke.

The invention is characterised in that a part of the pyrolysis gases isburned and used to simultaneously preheat the fluidised product to betreated and crack the tars contained in the pyrolysis gases.

The invention is further characterised by the use, in a. closed circuit,of spent gases, hereinafter called fumes, in combination with aninjection of Water in order to cool the fluidised solid productobtained.

The invention also concerns a new apparatus for carrying out theaforesaid method. This apparatus consists of a three-stage verticalretort, these three superposed stages being respectively intended forthe carbonisation of the fluidised coal, the partial combustion of thepyrolysis gases and the heating thereof, and the preheating of the coalfines by fluidising them with the gases coming from the preceding stage.

Other features and advantages of the present invention will become clearon reading the following escription with reference to the accompanyingdrawings, in which:

FIGURE 1 is a diagrammatic view of an installation for putting intopractice the method according to the invention, and

FIGURE 2 shows a specific embodiment of a new apparatus for carrying outthe method according to the invention.

This installation and this apparatus are designed for the carbonisationof fluidised coal, at temperatures approximately ranging between 930 F.and 1,650 F., in order to obtain a granulated semi-coke, sm'd coal beingpreheated to about 570 F. to 750 F., and air being added, if necessary,at a temperature which should be advantageously as high as possible, butwhich, in accordance with simple and conventional methods, will beusually in the neighbourhood of 930 F. The pyrolysis gas, heated to atemperature of 1,830" F. by partial combustion, is used for preheatingthe product.

The installation shown in FIGURE 1 essentially comprises a carbonisationreactor 1 making use of the fluidisation technique, a combustion chamber2, a drying and preheating chamber 3 also making use of the fluidisationtechnique and a cooling chamber 4.

The carbonisation treatment is effected in the reactor 1, supplied withhot crude, such as coal fines, from a conduit 5 end a feeder 6. Thefiuidising fluid (generally air) is supplied through a pipe 7 afterhaving been heated in the combustion chamber 2. The rate of fiow of thefluid and the rate of flow of coal fines are adjusted so as to maintainthe fluidised mass contained in the retort 1 at a temperature suitablefor the partial combustion thereof in the fluidised bed.

The reaction gases are discharged into the combustion chamber 2 througha pipe 8, after having been made dust-free in a cyclone separator 9. Thecollected dust is recycled into the reactor through a pipe 1%.

In the combustion chamber 2, the gases are partly burned by supplyingpreheated or non-preheated air through a pipe 11. The combustion is onlyvery partial so that the gas retains a high calorific power. Thecombustion is so regulated as to obtain a temperature of about 1,650 F.or more, so that the condensable products are cracked. The heated gasespass through a pipe 12 through which they are fed into the chamber 3with a view to drying and heating the fluidised crude product. Thedrying and preheating chamber 3 is fed with the crude product through apipe 13 and a feeder 14, which is in turn fed from a hopper 15. Theheated and dried product is transferred to the reactor 1 through thefeeder 6. The ratio of heated gas to coal in the chamber 3 is soadjusted that the temperature is maintained therein at a predeterminedlevel, generally comprised between 570 F. and 750 F. The partly cooledfumes are made dustfree by means of a cyclone separator 16 and evacuatedthrough 17. Suificient quantities of neutral gases are introducedthrough a conduit 19 to compensate the losses occurring in a closedcircuit 20 which is adapted to cool the fluidised final product in thecooling chamber 4, supplied With the treated product from the reactor 1through a conduit 21 and a feeder 22. The closedcircuit is cooled by acooler 23. The cooled product is extracted at 25 for further treatment.

The retort shown in FIGURE 2 comprises a carbonisation reactor 51 makinguse of the fluidisation technique, a combustion chamber 52 and a dryingchamber 53 also making use of the fluidisation technique.

The carbonisation treatment is carried out in the retort 51, suppliedwith heated crude product through a pipe 54 and a feeder 55. The fluidfor the fiuidisation treatment is introduced through a pipe 56 leadingfrom a heat exchanger 66. The rate of flow of the fluid and the rate offlow of fines are so adjusted as to maintain the fluidised mass in theretort 51 at the processing temperature by a partial combustion withinthe bed.

The gases issuing from the reaction chamber are discharged into thecombustion chamber 52 via channel 57. The partial combustion of thesegases is obtained by introducing preheated or non-preheated air throughthe pipe 58. The very partial combustion is so adjusted as to obtain atemperature of about l,650 F. or more, thus causing the condensableproducts to crack. A portion of the gases is transferred to the heatexchanger 69 through a pipe 59, and is then evacuated through a generalconduit 68. But the greater proportion of the gases originating from thecombustion chamber 52 is used for drying and heating the fluidised crudeproduct. For this purpose, a conduit 61 establishes a directcommunication between thecombustion chamber 52 and the drying chamber53. This drying chamber, having a fluidised bed, is supplied with thecrude product through a pipe 62 and a feeder 63, which is in turn fedfrom a hopper 64. The heated and dried product is transferred, as hasalready been stated, into the reactor 51 by way of the feeder 55. Theratio of hot gases to coal in the chamber 53 is so adjusted that thetemperature is maintained therein at a predetermined level, which willbe generally comprised between 570 F. and 750 F. The partly cooled gasesare discharged through 65 and pass into a cyclone separator 66, firomwhich the dust is recycled into the drying chamber at 67. The dust-freegases are evacuated through 68. Neutral cold gases are introducedthrough pipe in function of the losses occurring in a closed circuit 71which is provided for the cooling of the fluidised final product in acooling chamber 72, supplied with the treated product from the reactor5]. through a conpartial combustion to be efiected. This results in animproved yield of semi-coke and of gases. The quality of I the semi-cokeis improved through the decrease of its ash contents. The calorificpower of the gas is improved because of a lesser dilution by fumes(ntirogen and carbon dioxide).

ltiwill be noted, that, as is the case in most methods of carbonisationby the fluidisation technique, it is advantageous to preheat the air orthe processing gas. it will be noted that in the method according to theinvention, this preheating step can be effected either in parallel withthe preheating of the coal (FIGURE 2) or in series therewith (FIGURE 1).

The partial. combustion of the pyrolysis gases at a suflicienttemperature within the combustion chamber 2 64 or 72, combinedwithfluidisation bymeans of the fumes introduced in 19 or 72, isvaluable in case of carbonisation at low temperature, Where a veryreactive solid product is involved, which has to be cooled'very rapidlyin the absence of air, in order to avoid spontaneous re-ignitions. It isto be understood that this invention has just been described by way ofexplanation, without limitation of the same, and that variousmodificationscan be made therein without exceeding its scope, inparticular by modifying the carbonisation conditions and change thegasification rates by making use of other fluids'than air, such asoxygen, steam, oXydizing gases, or any other fluid, commonlyused, ortheir mixtures.

I claim:

An apparatus for the continuous carbonisation of 4 coal fines by thefiuidisation technique, said apparatus comprising a vertical retortincluding three chambers disposed in vertical alignment one above theother, and which starting from the bottom, consist of a reactor forfluidised treatment, a chamber for the post-combustion of the gases ofpyrolysis and a chamber for preheating by V iluidisation; means withinthe confines of saidiretort directly connecting the reactor forfluidised treatment and the post-combustion chamber of pyrolysis gasesand meansrwithin the confines of said retort directly connecting thepost-combustion chamber and the chamber for preheating by iluidisation;means for adding air into the post-combustion chamber; and'means fortransferring the product to be treated by gravity between the preheatingand reaction chambers.

2. An apparatus according to claim Land means for preheating air addedinto the post-combustion chamber.

3. 'An apparatus in accordance with claim 1, wherein thesecond-mentioned connecting means allows the passage of iluidisation gasinto the preheatingchamber at substantially the lowest level thereof.

4. A method for the continuous carbonization of fluidized coal finescomprisin forming a bed of a heated product to be treated, introducingan oxydizing fluid into the bed toproduce turbulence in the bed andcause a stabilized reaction by partial combustion of the said product,mixing air with gases originating from said reaction, said gases havingessentially the same constituents as when evolved, and causing a partialcombustion thereof, the temperature of the resulting gases of whichis'not less than about 900 C., to simultaneously cause a cracking ofcondensable products, and preheating said product to be treated in afluidised state by a portion of said resulting gases originating fromthe last mentioned partial combustion of the gases.

5. The method of claim 4, further comprising preheating the mixingair.

References Cited in the file of this patent UNITED STATES PATENTS1,551,956 Hubmann Sept. 1, 1925 2,131,702 Berry Sept. 27, 1938 2,480,670Peck Aug. 30, 1949 2,626,234 Barr et a1. Jan. 20, 1953 2,689,787Ogorzaly et a1. Sept. 21, 1954 2,899,365 Scott Aug. 11, 1959

4. A METHOD FOR THE CONTINUOUS CARBONIZATION OF FLUIDIZED COAL FINESCOMPRISING FORMING A BED OF A HEATED PRODUCT TO BE TREATED, INTRODUCINGAN OXYDIZING FLUID INTO THE BED TO PRODUCE TURBULENCE IN THE BED ANDCAUSE A STABILIZED REACTION BY PARTIAL COMBUSTION OF THE SAID PRODUCT,MIXING AIR WITH GASES ORIGINATING FROM SAID REACTION, SAID GASES HAVINGESSENTIALLY THE SAME CONSTITUENTS AS WHEN EVOLVED, AND CAUSING A PARTIALCOMBUSTION THEREOF, THE TEMPERATURE OF THE RESULTING GASES OF WHICH ISNOT LESS THAN ABOUT 900*C., TO SIMULTANEOUSLY CAUSE A CRACKING OFCONDENSABLE PRODUCTS, AND PREHEATING SAID PRODUCT TO BE TREATED IN AFLUIDISED STATE BY A PORTION OF SAID RESULTING GASES ORIGINATING FROMTHE LAST MENTIONED PARTIAL COMBUSTION OF THE GASES.